Fuses are the key to field repairing a digital I/O PLC card. In most cases, when a fuse blows in a digital PLC card it disables more than one output. If you see a group of 4, 8 or 16 points fail all at once, simply remove your module and test the internal fuses with an inexpensive Ohm meter.
Full Answer
What should I do if my plc is not working?
First, check that the PLC is receiving enough power from the transformer to supply all the loads. If the PLC is still not working, check for voltage supply drop in the control circuit or for blown fuses.
How to repair a digital I/O plc card?
The most common module sent in for repairs are discrete modules from 24 volts to 230 volts. Luckily, these are also the easiest to repair and cost the least. Fuses are the key to field repairing a digital I/O PLC card. In most cases, when a fuse blows in a digital PLC card it disables more than one output.
What is the primary focus of the troubleshooting process in plc?
The primary focus of the troubleshooting process in this case is to establish what the disconnect is between the internal situation (essentially, what the PLC thinks is happening) and the external situation (what’s actually happening).
How do you fix a blown fuse on a PLC card?
Fuses are the key to field repairing a digital I/O PLC card. In most cases, when a fuse blows in a digital PLC card it disables more than one output. If you see a group of 4, 8 or 16 points fail all at once, simply remove your module and test the internal fuses with an inexpensive Ohm meter.
Can a PLC be repaired?
0:411:29Allen Bradley SLC PLC Repair - YouTubeYouTubeStart of suggested clipEnd of suggested clipRepaired. We offer three repair turnaround options which may be as fast as the next business dayMoreRepaired. We offer three repair turnaround options which may be as fast as the next business day most repairs are pre-priced or may be sent to us for a free evaluation.
How do you solve a PLC problem?
0:316:59Electrical Troubleshooting & PLC Troubleshooting - YouTubeYouTubeStart of suggested clipEnd of suggested clipTwo test the system and verify possible causes once corrective action is taken follow through byMoreTwo test the system and verify possible causes once corrective action is taken follow through by monitoring the operation to make sure you have pinpointed the root.
How do you service a PLC?
PLC Maintenance ProceduresCheck environmental factors / operating conditions. ... Clear debris, dust, and buildup from your units. ... Clean or replace all filters installed in enclosures. ... Check all your connections for a tight fit, especially I/O modules. ... Inspect I/O devices for proper adjustments.More items...•
How do you know if a PLC is bad?
If the PLC is still not working, check for voltage supply drop in the control circuit or for blown fuses. If the PLC does not come up even with proper power, then the problem lies in the CPU, and this is very bad. The diagnostic indicators on the front of the CPU will show a fault in either memory or communications.
What causes a PLC to fault?
About 80 per cent of PLC failures are a result of field devices, Input/Output (I/O) module failure or power supply issues. Typically, these defects manifest themselves as a sudden process stop or irregularity of performance.
What are the problems of PLC?
Five Common Issues with PLCs & How to Solve ThemModule Failure of the Input/Output (I/O) System. Perhaps the most common problem affecting PLCs is a module failure of the input/output (I/O) system. ... Electrical Noise Interference. ... Corrupted Memory. ... Power Problems. ... Communication Issues.
What is a PLC in maintenance?
A PLC (Programmable Logic Controller) is the type of computer that controls most machines today. The PLC is used to control AND troubleshoot the machine. The PLC is the brain of the machine. Without it, the machine is dead. The maintenance technicians we train, are the brain surgeons.
What are the types of PLC?
PLC are divided into three types based on output namely Relay output, Transistor output, and Triac Output PLC.
What does PLC stand for in maintenance?
Why Is PLC Maintenance Important? Your programmable logic controllers (PLC) are critical to the smooth operation of your factory. That's why it's very important that they are up and running at peak efficiency every day.
How do you test a PLC?
Steps in PLC CommissioningCable connections must meet standards. ... Check the power supply. ... Check indicator lights of the PLC. ... Put PLC in a test mode. ... Check protective devices. ... Check emergency stop buttons. ... Check connection points of input and output devices. ... Test the software.
What are the 4 main components of a PLC?
– The Hardware components of a PLC are the Processor, the Power Supply, the Input/Output Modules, and a Programming Device.
Do PLCs go bad?
Despite these complexities, PLCs can also have problems. Common reasons why PLC control systems fail include module failure, power outages and bad network connections. PLC failure issues can also stem from overheating, moisture and electromagnetic interference.
What does PLC error mean?
A PLC communication error happens when the PLC doesn't respond to communication requests or responds negatively to such requests. A PLC communication error can occur between the programmable computer and the devices it controls or when the technician attempts to program the device from afar.
How do you troubleshoot a logic ladder?
0:115:04How to Troubleshoot a PLC - Ladder Logic - YouTubeYouTubeStart of suggested clipEnd of suggested clipEveryone today we'll take a look at troubleshooting a couple of plc. Examples I have two up here.MoreEveryone today we'll take a look at troubleshooting a couple of plc. Examples I have two up here. And what you'll notice is I have some set and resets on an output that's why eight.
How do you check PLC inputs and outputs?
If the PLC processor has an AC power source, check the input voltage; it should be within the manufacturer's recommended range. PLC processors actually operate on DC power, so that also must be checked. Measure each of the outputs of the DC power supply and check if the voltages are within the recommended ranges.
What would be the first step in troubleshooting a malfunctioning programmable logic relay?
The first step in troubleshooting input malfunctions is to check your inputs for proper wiring, identifying your PLC IO from the provided schematics. Then, typically, the problem source can be narrowed down by comparing the actual status of the suspect I/O with the controller status indicators.
What is a fuse in a PLC?
Fuses are the key to field repairing a digital I/O PLC card. In most cases, when a fuse blows in a digital PLC card it disables more than one output. If you see a group of 4, 8 or 16 points fail all at once, simply remove your module and test the internal fuses with an inexpensive Ohm meter.
What causes intelligent modules to fail?
Other common failures in intelligent modules are focused around serial and Ethernet communication ports. Communication wires may create antennas and can destroy communication driver-integrated circuits. If there is a secondary communication port unused, simply move your communication cable to a working port and reconfigure your device.
Why is PLC repair important?
PLCs are an essential part of any set of operations because they allow different electronic devices to connect and communicate. Without them, it’d be much more difficult to conduct tests and send and receive output. If you find your company’s PLC isn’t in working order, however, there’s no need to panic — even if you can’t immediately diagnose the issue.
What is the next step in cleaning a PLC?
Cleaning: The next-to-last step consists of cleaning the entire unit and giving it one last test to check its functionality. A detailed cleaning job lets us return your PLC in a near brand-new condition, repaired and ready for any application your company has for it.
Why Global Electronic Services for PLC Maintenance Service and PLC Repair?
Global Electronic Services is the company you want to employ for PLC repair and maintenance. Our factory-trained technicians are continuously learning the best techniques to help you get the most out of your PLC and other electronic devices. In addition to our highly experienced team, we offer benefits that are hard to find anywhere else.
What is an inspection PLC?
These physical connectors enable the PLC to receive new information and send data to other devices.
Who to call when PLC goes down?
If your electronic equipment is vital to your business, then knowing who to call when that equipment goes down is just as vital. For programmable logic controller (PLC) repair, the clear choice is Global Electronic Services.
Does PLC maintenance cost increase after repairs?
By keeping our PLC maintenance and repair transparent, we ensure there are no surprising costs — your quote won’t increase after repairs are complete. And if you go to a competitor with a lower price than ours, we’ll beat their charge by 10% per our Repair Price Guarantee. Free quotes and evaluations reduce the overall amount further, allowing you to reap the benefits of excellent PLC repair services without facing unreasonable costs.
Why is my PLC not reading?
External factors, such as the aforementioned frequency interference and power disruptions, can corrupt the memory of a PLC. When this happens, the code within the PLC may become unreadable, or the PLC may not be able to read properly when it’s booted up from an unintentional shut down. The safest and most efficient way to deal with this problem is to ensure all data is copied to a redundant storage device that is kept away from interference, high temperatures and humidity.
What is the most common problem affecting PLCs?
Perhaps the most common problem affecting PLCs is a module failure of the input/output (I/O) system. The primary focus of the troubleshooting process in this case is to establish what the disconnect is between the internal situation (essentially, what the PLC thinks is happening) and the external situation (what’s actually happening).
Why are PLCs important?
As PLCs have increased in functionality and decreased in cost, they have become mainstream in the world of automated systems, and have become fundamental to monitor and control both individual machines and complex processes.
What is the effect of foreign signal interference on a PLC?
Foreign signal interference resultant of either electromagnetic interference (EMI) or radio frequency interference (RFI) can greatly affect the performance and longevity of a PLC. The potential for EMI is greatly increased if there is a large motor or similar machine that’s activated close to the PLC, or if lightning strikes nearby.
What is the communication issue with PLC?
In order to function properly, PLC devices must be in constant communication with surrounding devices, such as peripherals, Human-Machine Interfaces and other smart equipement. This communication is facilitated via Ethernet cables and requires a safe, stable and consistent connection.
How to prevent power loss?
The most effective way to avoid these problems resultant of power loss is to install backup power sources that activate when the primary power source becomes compromised. Many facilities also employ batteries in their PLCs, which will prolong power until they can be shut down properly.
Is a PLC reliable?
While PLC devices have become increasingly mainstream and reliable, encountering the occasional problem is inevitable. This is where quick and efficient troubleshooting skills are paramount to your job as a PLC technician.
How to separate power conditioning PCB from main board?
Using a small flat blade screwdriver to push in the side tabs , it's easy to pull the enclosure apart and separate the power conditioning PCB from the main board.
What is the first component of a circuit?
The first component in the circuit is a fuse, designed to limit the damage from precisely this type of mishap. Using a multimeter to check for continuity showed that it was in fact blown, as one would expect. I went ahead and jumpered it out with a wire wrap connection.
Can you disassemble a Siemens S7-1200?
Fortunately, the Siemens S7-1200 series PLCs are quite easy to disassemble, and I was able to replace the damaged components and restore it to a proper working condition. I definitely wouldn't trust this refurbished PLC to run a critical system, but for testing code in our lab, it should be just fine. I would also recommend reaching out to the manufacturer if you are running into issues with a production PLC, keeping in mind that any warranty may be voided if you attempt to fix it yourself.
Why is my PLC not coming up?
If the PLC does not come up even with proper power, then the problem lies in the CPU, and this is very bad.
How many methods of troubleshooting PLC?
PLC troubleshooting can be performed in many different ways and as the engineer’s experience always plays the major role in successful resolving of such issues, five methods have been developed.
How to tell if a field meter is faulty?
First, close the field device and measure the voltage to the input module. The meter should display the voltage of the signal (e.g., 120 volts AC). If the proper voltage is present, the input module is faulty because it is not recognizing the signal. If the measured voltage is 10–15% below the proper signal voltage, then the problem lies in the source voltage to the field device.
Why does my inductive load blow?
The inductive loads may be generating voltage and current spikes, in which case, external suppression may be necessary. If the module’s fuse blows again after it is replaced, the problem may be that the module’s output current limit is being exceeded or that the output device is shorted.
What happens if both LEDs are not on simultaneously?
Like the power and logic indicators in an input module, if both LEDs are not ON simultaneously, the output module is malfunctioning. LED indicators greatly assist the troubleshooting process. With both power and logic indicators, the user can immediately pinpoint a malfunctioning module or circuit.
What is the purpose of PLC output interface?
Like the troubleshooting of PLC inputs, the first step in troubleshooting outputs is to isolate the problem to either the module, the field device, or the wiring.
What is a good idea to keep a stock of replacement parts on hand?
1. Troubleshooting ground loops. It is a good idea to keep a stock of replacement parts on hand. This practice will minimize downtime resulting from component failure. In a failure situation, having the right spare in stock can mean a shutdown of only minutes, instead of hours or days.
What does it mean when a PLC goes to stop mode?
Some times, when the CPU of our PLC detects an unacceptable condition at the programme’s flow , then it goes to “STOP” mode and possibly a led flashes and indicates this malfunction.
Why do I say modern automation systems?
I said modern automation systems because in the past (before PLCs/other compact controllers be well known and used by automation development companies), the control of an automation system was going on only with relays.
What happens if the relay is OK?
If the relay is OK, then maybe we have problem with the motor that is responsible for closing the door. We should check motor for its status (motor coils, mechanical parts)
Why does a power unit tell us if a motor is overheating?
For example, if a motor is overheated, the drive will inform us about it because it checks continuously the temperature sensor (eg thermistor) which is located inside motor’s enclosure.
When we have power units (drives) in our automation system in order to drive a motor, should we have?
Generally, when we have power units (drives) in our automation system in order to drive a motor, then we should have together the manual of the specific power unit.
Should we find the drawings of automation system?
We should already have find the drawings of automation system in order to see the connections for the components we want to check.
Do automation systems have PLCs?
Before we proceed, we agree that modern automation systems have PLCs for controlling the application. If we have a small application then the system possibly has a microPLC (or nanoPLC) or another type of compact controller (many times this depends of the application).
How to check if a PLC is working?
If these are all working correctly move on to checking the outputs below. Otherwise test that power is coming back into the PLC inputs with a meter.
What voltage is needed for main PLC?
Check to ensure main PLC power is being applied (120vac or 24vdc) many times their is a main power LED on the PLC to indicate so. Also check that it is the correct voltage being applied.
How to tell if relay contact is bad?
If the relay contact is found to be bad. Check with your meter and the power off to ground from the circuit that may be shorted. If its less then 40 ohms or so you most likely have a short to ground. Find the short or bad coil and repair. Then sometimes another relay may be swapped out that was not being used on the board Many times you have to unsolder and resolder in the bad relays place
How to check if a cell is faulty?
Such as a tool changer, pallet changer or magazine area. Look through the electrical prints for the possible proxes or devices that may be faulty.
Can you actuate a CNC machine with an M code?
At this point it may be necessary to actuate the machine either by an M-code if it is a CNC or if it is a PLC direct then run the functions you are trying to perform.
